yes and no if a white person mimicking a japanese accent is racist then the reversal should also be racist but i personally wouldnt class impersonation as a racist act providing the impersonation is fair to the impersonated ie saying do you know de wae in an african accent isnt racist but doing a minstrel impersonation as well as the accent would be racist due to the context saying nigger when discussing what slave owners said about their slaves isnt racist but calling black people niggers is the context defines the action